Heating Furnace Research Articles

Fabrication of PVTF Films with High Piezoelectric Properties Through Directional Heat Treatment

Piezoelectric materials can realize the mutual conversion of mechanical energy and electric energy, so they have excellent application prospects in the fields of sensors, energy collectors and biological materials. The poly(vinylidene fluoride) (PVDF)-based polymers have the best piezoelectric properties in the piezoelectric polymer, but they still have a large room for improvement compared with the piezoelectric ceramics. Improving their content of the polar β phase has become a consensus to polish up the piezoelectric performance. Most available studies construct hydrogen bonds or coulomb interactions between the surface of the dopant and molecular chains by doping, which promotes the molecular chains arrangement and thus facilitates the formation of the polar β phase. Recent studies show that the ordered arrangement of molecular chains is also important for piezoelectric properties. At present, the main way to improve the piezoelectric performance of PVDF is through doping or complex heat treatment process. Here, the poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) film was treated by directional heat treatment which used a heating table. Compared with uniform heat treatment like muffle furnace heat treatment, this simple vertical temperature gradient has many advantages for the content of the β phase and the crystallinity of P(VDF-TrFE). The results of the experiment showed that the content of the β phase of films remained at about 88%. When the film thickness was limited to 100 μm and the heat treatment temperature was limited to 200 °C, its crystallinity could reach 75% and the highest piezoelectric coefficient could reach 33.5 ± 0.7 pC/N. P(VDF-TrFE) films based on the experimental methods described above that show great potential for future applications in electronic devices and biomedical applications.

Role of constraint volume and heat flux on the design of evaporator tubes of steam generator by entropy generation minimization

This paper proposes a design methodology for evaporator tubes of a steam generator by applying the entropy generation minimization (EGM) approach. A two-phase flow-based entropy generation model for steam generator evaporator tubes is developed, with coolant volume as a constraint. For a target steam generation rate, the total entropy generation of the evaporator circuit is minimized using system volume and furnace heat flux as two constraints. It is observed that for a fixed steam generation rate, with increasing evaporator diameter, the furnace height decreases while the cross-sectional area increases. The analysis reveals that for a steam generation rate of 100 kg/s and a fixed circuit volume of 47 m3, increasing the heat flux from 36 to 50 kW/m2 shifts the EGM point from an evaporator diameter of 62 mm to 84 mm, respectively. On the other hand, the minimum point shifts to a diameter of 43 mm when the heat flux is decreased to 25 kW/m2. The present study concludes that the selection of the constraint volume for designing the evaporator downcomer circuit for a target steam generation rate should be done based on the available furnace heat flux to choose the most efficient design.

The influence mechanism of thermal invasion on spontaneous combustion of different coals using continuous adiabatic heating and non-isothermal oxidation method

Within deep coal mines, the elevated ground temperature has the potential to induce thermal invasion, thereby exacerbating coal spontaneous combustion (CSC). To investigate the influence mechanism of thermal invasion on CSC, experiments were conducted using coals of different metamorphic degrees (lignite, bitumite, and anthracite) with a continuous adiabatic heating and non-isothermal oxidation method in an oxidation furnace and an in-situ ESR spectrometer. Thermal invasion markedly enhanced the inherent susceptibility of spontaneous combustion of coals by increasing the oxygen consumption rate and lowering the apparent activation energy. This enhancement results from active free radicals generated during thermal invasion which accelerated coal-oxygen reactions during non-isothermal oxidation. These free radicals were found to be mainly carbon-centred radicals adjacent to an oxygen atom (alkyl radicals). An increase in both the g-factor value and free radical concentration was observed with thermal invasion temperature and invasion duration, especially in lignite, leading to a surge of free radical concentration during non-isothermal oxidation. The active free radicals generated during thermal invasion can easily react with oxygen, providing heat for coal-oxygen reactions and enabling rapid free radical generation. These findings offer insights for developing CSC evaluation and prevention strategies in deep mines where high ground temperatures are encountered.

Effect of Melamine on the Oxygen Reduction Reaction in the n(111)-(111) Series of Pt3Co

Abstract Enhancement of the oxygen reduction reaction (ORR) activity is an important subject for the development of fuel cells. In this study, we prepared the n(111)-(111) series of Pt3Co single crystal electrodes using an induction heating furnace and investigated the ORR in 0.1 M HClO4 using the rotation disk electrode (RDE). The specific activity of the ORR (j k) increased monotonously with increasing terrace width n on the n(111)-(111) series of Pt3Co, showing the highest activity on Pt3Co(111). The value of j k of Pt3Co(111) was 59-fold higher than that of Pt(111) at 0.95 V(RHE). This trend was different from those of the same series of Pt, Pt3Co, and Pt3Ni reported previously. Furthermore, the ORR activity was improved on all electrodes by adding melamine to the electrolytic solution. Melamine was preferentially adsorbed at the terrace edge. Pt3Co(553) n = 5 showed the highest activity. The values of j k at 0.95 V(RHE) were 23- and 3.3-fold higher than those of Pt(553) n = 5 and Pt3Co(553) n = 5 without melamine modification, respectively. The durability of Pt3Co(553) n = 5 with melamine was improved 8.0-fold. Graphical Abstract

Combustion characteristics of regenerative heating furnace for oil shale retorting based on top air supply

To comply with stricter air pollution standards, a new top air supply technology was proposed. Through numerical simulation, the effects of the number of air nozzles (A), air inclination (B) and fuel gas nozzle position (C) on the average temperature in the furnace, incomplete combustion heat loss and NO emission were analyzed. The research results show that the number of air nozzles has an important impact on the vortex in the pre-combustion chamber, the installation position of the fuel gas nozzles has a certain impact on the vortex formed in the combustion chamber, while the inclination of the air nozzles has no obvious effect on the vortex formation; the mean furnace temperature is most significantly affected by the interaction of factors A and B(A × B), and other factors have relatively little influence; the incomplete combustion heat loss at the exit of the combustion chamber is mainly dominated by factor A, followed by factors A × B and C. For the NO emission value at the exit of the combustion chamber, factors A and A × C have a significant impact, factors A × B also have a certain impact, and other factors can be ignored.

Fast simple determination of nitrogen in reduced graphene oxide by pulse furnace heating combined with thermal conductivity detection technique

The fast accurately determining the contents of various elements in reduced graphene oxide (rGO) has long been the most important research topic in the field of analytical chemistry for a long time. In this study, a new method was developed for fast and simple determination of total nitrogen content in rGO via pulse furnace heating combined with a thermal conductivity detection technique. Two key parameters, extraction power and sample weight were optimized experimentally. A nitrogen release curve was obtained through pulse furnace heating combined with thermal conductivity detection. The quantification limit of nitrogen element was calculated based on the results of the multiple blank experiments, and the accuracy and precision of the new method were verified by measuring nitrogen contents in rGO samples. The accuracy of this method was verified through X-ray photoelectron spectroscopy and a CHNOS analyzer comparisons. This is the first study, in which pulse furnace heating combined with thermal conductivity detection was used to determine the total nitrogen content in rGO.

Production of carbon storage sintered body from fly ash by microwave heating

Environmental11fly ash (FA), concrete sludge cake (CSC), X-ray fluorescence (XRF), scanning electron microscope (SEM). concerns have spurred research into replacing thermal power with microwaves in chemical plants to promote sustainability. However, there is a lack of established methodologies for scaling up microwave heating furnaces through analytical and experimental approaches. In this study, a sintered material intended for use as roadbed material was developed using concrete sludge cake and fly ash from a thermal power plant. This material can incorporate up to 10 % carbon with the addition of certain additives. Furthermore, a microwave heating furnace was designed based on parametric analysis to ensure both homogeneity and efficiency in operation. The developed microwave furnace, with a capacity of 30 kW, is capable of sintering 640 kg of fly ash daily in a uniform manner. Employing the methodology outlined, microwave furnaces can be optimised to accommodate specific materials, facilitating the design of systems suitable for the electrification of chemical plants.

Study on Natural Characteristics of Coal Gangue Oxidation under the Action of Water.

The exposed accumulation of coal gangue undergoes changes when it is soaked by rainwater, exhibiting varying tendencies for spontaneous combustion in different precipitation regions. This study investigates the effects of moisture on the oxidation and spontaneous combustion of coal gangue in high-sulfur coal gangue from the Qipanjing area of Inner Mongolia. Initially, coal gangue samples were subjected to soaking and air-drying treatments at different moisture contents. The dried coal gangue samples were then placed into a self-designed programmable heating furnace for thermal experiments, during which the gases generated were collected and characterized using gas chromatography. By comparing the oxygen consumption and volume fractions of gases such as CO, CH4, and C2H6 produced from coal gangue treated at different moisture contents, it was found that the low-temperature oxidation characteristics were optimal at a moisture content of 25%. At this level, the initial formation temperatures of gases like CO, CH4, and C2H6 were the lowest, with peak concentrations observed at 390 °C. Conversely, when the moisture content exceeded 70%, a significant amount of combustible material in the coal gangue was dissolved and dispersed by water, leading to a marked decrease in the concentrations of indicator gases produced at 390 °C. In fact, these concentrations fell below those of the control group, which was not subjected to water soaking or subsequent drying. The water immersion treatment also lowered the initial temperature points for the generation of various indicator gases by approximately 15 °C, making spontaneous combustion more likely.

Fuzzy Logic Approach for Modeling of Heating and Scale Formation in Industrial Furnaces.

Heating steel charges is essential for proper charge formation. At the same time, it is a highly energy-intensive process. Limiting the scale formed is critical for reducing heat consumption in this process. This paper applies fuzzy logic to model heating and scale formation in industrial re-heating furnaces. Scale formation depends on the temperature of the initial charge, heating time, excess air coefficient value, and initial scale thickness. These parameters were determined based on experimental tests, which are also the inputs in the model of the analyzed process. The research was carried out in walking beam furnaces operating in hot rolling mill departments. To minimize the excess energy consumption for heating a steel charge in an industrial furnace before forming, a heating and scale formation (HSF) model was developed using the fuzzy logic-based approach. The developed model allows for the prediction of the outputs, i.e., the charge's final surface temperature and the scale layer's final thickness. The comparison between the measured and calculated results shows that the model's accuracy is acceptable.

Magnesium ion substitution in various calcium phosphates: A way towards bone regeneration

This study examined the gradual replacement of Ca2+ with a small amount of Mg2+ ions (0–1 wt%) in selected calcium phosphates commonly used in regenerative medicine: hydroxyapatite Ca10(PO4)6(OH)2, brushite CaHPO4∙2H2O, and β-tricalcium phosphate (βTCP) Ca3(PO4)2. These compounds were obtained using precipitation reactions from aqueous solutions, followed by appropriate thermal treatment (drying or furnace heating). The microstructure and physicochemical properties of the materials were thoroughly analysed using powder X-ray diffraction (PXRD), scanning and transmission electron microscopy (SEM and TEM), and mid-infrared spectroscopy (FT-IR). Additionally, the release of Mg2+ ions from the selected materials was investigated, and a preliminary in vitro toxicity assessment was performed.The results showed that the introduction of magnesium ions up to 1 wt% was achieved with relatively high efficiency (63–82 % for brushite, 77–97 % for hydroxyapatite, and 88–100 % for β-tricalcium phosphate). The entire series of hydroxyapatites was phase-homogeneous, but monetite was observed as an additional phase in the case of brushite samples. In contrast, several βTCP samples were contaminated with a small amount of calcium oxide and hydroxide. The incorporation of Mg2+ ions significantly impacted the unit cell parameters of each type of calcium phosphate and the ultrastructure of the obtained powders. With an increase in the amount of introduced magnesium, the resulting crystals became smaller and showed a greater tendency to form aggregates. The obtained results indicate that it is possible to obtain calcium phosphate materials containing Mg2+ ions with a gradual release of ions. The fastest ions release occurred from the brushite sample, while the slowest was from the apatitic powder, which is in great accordance with the solubility of the materials. All samples, except for Mg0.5-Bru, were non-cytotoxic.

Raman Thermometry for Temperature Assessment of Inorganic Transformations During Microwave Heating

ABSTRACTMicrowave heating is an intriguing method for the synthesis of inorganic solids offering a variety of advantages over conventional furnace heating, such as fast heating and cooling rates as well as volumetric and selective heating of precursors. However, there are many open questions regarding this “black‐box” process, and insights into the effect of microwave radiation on different types of solids are generally missing. In situ Raman spectroscopy is a powerful technique to unravel chemical transformations and identify intermediate species during microwave solid‐state syntheses. A major challenge is the temperature measurement under microwave conditions because (metallic) thermocouples cannot be used and optical pyrometry has significant drawbacks. In contrast, Raman thermometry is a viable method that relies on the temperature‐induced shift of Raman signals. Here, we use this method to estimate the temperature during microwave heating of a model system (titania) that undergoes a phase transition at temperatures >800°C. The estimation is derived from a flexible double exponential calibration function applied to Raman spectroscopic peak shifts in the temperature‐resolved furnace heating data, which was found to describe two titania modes (one anatase and one rutile) extremely well. Based on a detailed error and uncertainty analysis, we suggest options to further optimize Raman thermometry for use in high‐temperature microwave heating conditions.

The corrosion behavior of Al2O3-SiO2 refractory in reducing atmosphere

Hydrogen metallurgy technology is essential for reducing CO2 emissions. Hydrogen (H2) serves as an ideal energy carrier to replace carbon-based fuels, producing only water as a byproduct. Al2O3-SiO2 refractories are commonly used in hydrogen metallurgy technology, including in technologies like HyCROF(Hydrogen-enriched Carbonic oxide Recycling Oxygenate Furnace) and gas heating furnaces. It is important to systematically study their corrosion in high-temperature reducing gas environments. The results indicated that the Al2O3-SiO2 refractory remained stable in pure H2 atmosphere at temperatures below 1200 °C. However, SiO2 and mullite were reduced by H2 when the temperature was increased above 1200 °C. Carbon precipitation was observed in both pure CO atmosphere and H2-CO mixed atmosphere, resulting in an increase weight of the sample. Additionally, the sample developed mullite whiskers after heating treatment at 1200 °C in H2-CO mixed atmosphere. This study aims to clarify the corrosion mechanism of Al2O3-SiO2 refractory in reducing atmosphere and to provide a theoretical basis for the selecting and optimizing refractories for hydrogen metallurgy technology.

The Impact of Hydrogen on Flame Characteristics and Pollutant Emissions in Natural Gas Industrial Combustion Systems

To improve energy savings and emission reduction in industrial heating furnaces, this study investigated the impact of various molar fractions of hydrogen on natural gas combustion and compared the results of the Non-Premixed Combustion Model with the Eddy Dissipation Combustion Model. Initially, natural gas combustion in an industrial heating furnace was investigated experimentally, and these results were used as boundary conditions for CFD simulations. The diffusion flame and combustion characteristics of natural gas were simulated using both the non-premixed combustion model and the Eddy Dissipation Combustion Model. The results indicated that the Non-Premixed Combustion Model provided simulations more consistent with experimental data, within acceptable error margins, thus validating the accuracy of the numerical simulations. Additionally, to analyze the impact of hydrogen doping on the performance of an industrial gas heater, four gas mixtures with varying hydrogen contents (15% H2, 30% H2, 45% H2, and 60% H2) were studied while maintaining constant fuel inlet temperature and flow rate. The results demonstrate that the Non-Premixed Combustion Model more accurately simulates complex flue gas flow and chemical reactions during combustion. Moreover, hydrogen-doped natural gas significantly reduces CO and CO2 emissions compared to pure natural gas combustion. Specifically, at 60% hydrogen content, CO and CO2 levels decrease by 70% and 37.5%, respectively, while NO emissions increase proportionally; at this hydrogen content, NO concentration in the furnace chamber rises by 155%.

Research and Application of Online Electromagnetic Heating System with Internal Penetration in Oil Pipeline at Well Site

Abstract In response to the current situation of heating crude oil in the oil pipeline of Changqing Oilfield, most of the well sites have no associated gas, gas heating furnaces have been discontinued, and coal-fired heating furnaces pollute the environment. A study was conducted on the online through type heating system for the oil pipeline in the well site, with a focus on the composition and function of the digital heating system for the through type oil pipeline in the well site. The through type online heating system for the oil pipeline in the well site is mainly composed of a variable frequency electromagnetic controller The online controller and internal heating cable are composed of three parts. The oil pipeline generates heat by itself, while preventing the crystallization of paraffin and scale in the oil pipeline under the action of alternating electromagnetic fields, which is not easy to form wax. In 2023, on-site application was carried out on two oil pipelines in the Tongzhai operation area of the Third Oil Production Plant in Changqing Oilfield, replacing the existing gas heating furnaces and coal-fired heating furnaces to heat and transport crude oil in the oil pipelines. It does not generate heat itself and has a long service life. Due to the high thermal efficiency of the heat source coming from the inside of the oil pipeline, the buried pipeline renovation can be installed without breaking the soil. The flexible internal cable reduces the difficulty of construction and is safe and environmentally friendly, At the same time, it can remotely monitor the temperature of crude oil in the oil pipeline and the wellhead backpressure online.

Research and Application of Electromagnetic Heating Device for Digital Well Site Crude Oil Export

Abstract Most well sites have discontinued using the associated gas-fired furnaces in response to the current situation in the oil fields. Coal-fired heating furnaces are environmentally polluting and prohibited due to local environmental regulations. These two heating methods can cause high costs, poor heating efficiency, and environmental pollution, which cannot be achieved through remote digital monitoring. Research has been conducted on the digital electromagnetic heating device for crude oil in the well site, focusing on introducing its main components and functions, including the electromagnetic heating body, frequency conversion control cabinet, and digital remote monitoring terminal. This device provides one-way internal heating without a heat source, resulting in high thermal efficiency, safety, environmental friendliness, and energy conservation. It comprehensively addresses the drawbacks of traditional electric heating, characterized by low efficiency, susceptibility to damage, and difficult maintenance. In 2022, it was applied at three well sites in the Tongzhai operation area of the Third Oil Production Plant of Changqing Oilfield, replacing the existing gas-fired and coal-fired heating furnaces to heat crude oil, as well as heating the heating belt and various electric heating pipes. This device is highly efficient, safe, environmentally friendly, and energy-saving. Additionally, the temperature and pressure of electromagnetic heating crude oil can be digitally and remotely monitored.

СВОЙСТВА ЭМУЛЬСИЙ ПЕЧНОГО БЫТОВОГО ТОПЛИВА

The features of household furnace heating fuel and its mixture with diesel fuel distillate in various concentrations are considered. By intensively mixing diesel distillate into household heating fuel, emulsions based on household furnace heating fuel were obtained, which contain from 10 to 50 % of secondary distillate diesel distillate. Such parameters as flash point, ignition point, density and viscosity were determined. The results of the study confirmed the efficiency of adding diesel fuel distillate.

Полициклические ароматические углеводороды в снежном покрове заповедных территорий Республики Коми

We studied the content of polycyclic aromatic hydrocarbons (PAHs) in snow cover of protected northern areas Komi Republic. PAHs in snow were determined by high-performance liquid chromatography. Insignificant PAHs levels in the range of 30–46 ng/L were found in the snow cover of protected areas. Naphthalene and phenanthrene were the main PAHs in the snow cover. Light PAHs were mainly present in dissolved form. The heavy PAHs in the snow cover were present in trace amounts and accumulated on the aerosol particles. Low toxicological activity was observed in all tested samples. The natural, non-pyrogenic origin of the PAHs was established on the basis of their diagnostic ratios. This may be an indication that PAHs enter the snowpack mainly through transformation of plant biomass and global air mass transport. The PCA showed a significant similarity of the PAH composition of all investigated sites. All the above facts allow relating the studied areas to background. It was found that the level of low-volatility PAHs entering the protected areas in 2023 is the same as the level of entering the background areas of the taiga zone of the Komi Republic in 2005–2007. The highest content of heavy PAHs and toxicological activity was found in the snow cover near the Yaksha settlement in the Pechoro-Ilychsky Reserve. Aerosol polyarenes were the main contributors to PAH toxicity. In comparison with low-intensity roads near the “Paraskiny Lakes” Reserve, it is shown that furnace heating has a greater effect on the PAHs composition in the snow cover.

Critical current density of high-temperature superconducting ceramics BSCCO Bi-2223

In the paper the results of the study on the synthesis of high-temperature superconducting ceramics of nomi- nal composition Bi1.6Pb0.4Sr2Ca2Cu3Oy by various methods were presented based on amorphous phases using glass-ceramic technology and solid-phase method. For comparison, amorphous phases were obtained in two ways. In the first case, a heating furnace of a special design was developed to obtain an amorphous phase, which provides melting without using a crucible. The heating of the initial samples for melting is carried out due to the combined effect of the convection heat flux and the radiation of heating elements, which consists of the IR region of the spectrum at a melting temperature in the spectral range of 1300–1350 nm. In the se- cond case, melting is carried out under the influence of broadband optical radiation, including UV, visible and IR spectral regions. The production of glassy precursors is carried out by draining the melt onto a quenching device in the form of a propeller made of stainless steel. Studies of the formation rate of the superconducting high-temperature phase Bi-2223 were carried out in the same temperature conditions at 848–850 °C with in- termediate grinding every 24 hours and the study of the phase composition by X-ray diffraction method. Studies showed that the glass phase-based method ensures the completeness of the formation of the high- temperature phase Bi-2223 and the rate of its formation is significantly higher than by the solid-phase method (2.5–3 times). Studies of the critical density of the transport current have shown that the current value is 7.05×103 mA/cm2, (measured by the criterion of 1 µV/cm), which is significantly higher compared to other methods.

Thermal deviation mechanisms for coupled heat transfer between the combustion side and the furnace tube side in the tubular heating furnace

Temperature deviation significantly affects the safe operation of tubular heating furnaces. This is attributed to the inevitable temperature difference between the flue gas and the working medium on the tube side. To date, little research has considered the dynamic heat transfer between the furnace body and the tubes in tube furnaces, and even less attention has been paid to the thermal deviation within tube furnaces. To optimize the operational parameters of the heating furnace, a comprehensive heat transfer model is established in this paper to numerically couple the heat transfer between the combustion side and the working medium on the tube side in tube furnaces. A hydrogenation feed heating furnace with a processing capacity of 600,000 tons per year in a chemical enterprise is selected as the subject of study. Using Fluent software, on the basis of coupled simulation, a non-uniformity coefficient of temperature distribution is introduced to characterize the thermal deviation within the furnace. The impact of the thermal load and hydrogen doping in the fuel gas on the thermal deviation within the furnace is analyzed. The numerical results demonstrate that with an increase in thermal load, the flame structure in the furnace gradually becomes concentrated, the average temperature of the flue gas increases, and the outlet temperature of the furnace chamber increases by 19%, with the thermal efficiency decreasing by 5.11%; at the same time, the overall non-uniformity coefficient of the temperature distribution in the furnace fluctuates irregularly, indicating a nonlinear relationship between the thermal load and the thermal deviation within the furnace. With an increase in the hydrogen content in the fuel gas, the flame structure in the furnace becomes more dispersed, the average temperature of the flue gas increases, but the combustion efficiency of the heating furnace exhibits irregular fluctuations; the thermal deviation within the furnace initially increases and then decreases, with a lower non-uniformity coefficient of temperature at 50% hydrogen content, which is 2.48% lower than at 40% hydrogen content. Under both conditions, the thermal deviation primarily leads to localized hot spots in the radiant furnace tubes and uneven temperature distribution in the convection section, with a minimal impact on the thermal efficiency of the heating furnace.

Technical Analysis of the Possibility of Burning Hydrogen in Furnaces of the Metallurgical Sector

This article analyses the possibility of using hydrogen as fuel in furnaces used in the metallurgical industry. The research was conducted for a selected continuous furnace. For this purpose, based on actual measurements, a heat balance of the furnace was prepared to determine its energy indicators. These values were used to verify the developed numerical model in IPSEpro 7.0 software. Numerical calculations were performed for three variants: pure natural gas; 30% hydrogen, 70% natural gas; and 100% hydrogen. The determined values of gas and combustion air streams allowed for achieving the assumed charge temperature in the heating technology. Calculations of the impact of the excess combustion air ratio on process parameters were also carried out. It was found that no changes are required in the exhaust gas removal system, but verification of the fan supplying air to cool the exhaust gases before the recuperator is necessary. The amount of hydrogen required to fuel the continuous furnace also increases significantly (nearly threefold), which may also affect operating costs. At the same time, the emission of carbon dioxide into the atmosphere is completely reduced, which may be an important criterion when considering modernization options for heating furnaces in the metallurgical industry.